LASIK (Laser-assisted in situ keratomileusis) involves treating nearsightedness, farsightedness or astigmatism by reshaping the eye’s cornea to alter the way the eye refracts light. LASIK involves creating a flap, removing a defined amount of corneal tissue by an excimer laser, and replacing the flap. In standard LASIK with a mechanical microkeratome, the flap is created by a blade; in bladeless LASIK, the newer type, the flap is created by a femtosecond laser.

“At six months after surgery, there are no differences between the eyes that had bladeless or microkeratome LASIK with respect to visual acuity, contrast sensitivity, or in perception of stray light or glare, such as the glare from oncoming headlights,” says Sanjay Patel, M.D., Mayo Clinic ophthalmologist and study investigator.

The study followed 20 patients who received LASIK for nearsightedness or astigmatism. Each patient was treated with microkeratome LASIK in one eye and bladeless LASIK in the other eye. The researchers found no difference in subbasal nerve density between types of surgery, though the density decreased after both treatments compared to density before LASIK. Corneal sensitivity did not differ between microkeratome and bladeless LASIK. Subbasal nerve density and corneal sensitivity do not impact vision, but rather the potential to heal from a scratch or other injury to the eye.

High-contrast visual acuity, the capability to see fine details, and contrast sensitivity, the ability to perceive contrast in objects and their environments, also did not differ between LASIK types. The researchers found corneal backscatter was greater with bladeless LASIK for the first three months after surgery, yet the patients perceived no difference in vision after three months between their eyes treated with bladeless or microkeratome LASIK.